The Boston school system is failing to adequately teach thousands of students who speak limited English and provide them with rigorous coursework, nearly five years after promising the US government it would overhaul programs to comply with civil rights laws, according to an ongoing federal review obtained by the Globe.

The violations are so widespread — prompting repeated visits by federal investigators over the last few months — that the school system is increasingly concerned that the federal agencies might head to court to force compliance.

Continue reading below

The situation is the most dire in the middle grades and the high schools, where 49 percent of students known as English-language learners are receiving insufficient levels of specialized instruction or none at all, according to the latest review by the US departments of Education and Justice, dated March 2. And 24 percent of elementary school students wit………….